Sea Cocks Option or Not? Pros vs Cons

[philipmclaren1]

I have been researching sea cocks tonight and i must say having a hole drilled into the hull freaks me out a little bit.
I would like to know your thoughts on this matter.
Would it be better to have a holding tank of sea water that i could fill by pumping water into from a hose directly over the side? To me this would seem a wiser option as there would be no hole below the water line so less chance of a leak. I could then pump out the waste from another holding tank directly into the ocean from a hole above the sea line.
Researching engines i see that you can have a direct feed or a enclosed system to cool. Surley again it would be safer to have no sea cock?
I guess what i am trying to say is am i just freaking out over nothing and should i fit a sea cock or not.
Advice gladly received.